Custom bolt carrier milling/lathe work ?

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Joined: Sat Dec 26, 2020 11:38 am

Custom bolt carrier milling/lathe work ?

Post by SockToy » Sat Dec 26, 2020 12:56 pm

Hi all,

If any of you do bolt carrier work, or could recommend an individual or firm that does, I'd appreciate it.

I am left eye dominant, and there are very few options for a left handed NY/NJ legal side charging rifle.

I'm hoping to enable a left hand eject Bolt Carrier group ('BCG') milled/lathed to fit a fightlite SCR lower, by removing the buffer extension and adding a dowel for a 'rat tail'.

I could supply all parts for alteration (LH BCG, dowel, tail), or happily pay to re-mill young parts, whatever works. BCGs are available in various grades of steel, or even aluminium, so there are options available.

Effectively, I am looking to (re)manufacture this: ... ft-handed/

To match the rear pattern of this:

if you're not familiar with this, essentially the mechanism has three relevant parts:
  • 1. An upper, often 7075 billet, milled to accept a barrel attached to the front, a stock attached to the back, and a lower (containing handle, trigger and magazine) attached to the bottom - surprirse!
    2. A bolt carrier group, or 'BCG' that slides freely within the upper, carrying a bullet to the barrel, and aligning the shell with the ejection port on the upper once the bullet is fired, the bolt with the magazine when a new bullet needs loading and gas ports on the bolt carrier group with gas ports on the upper - the gas ejected by the bullet during firing is (partly) what drives the BCG back into the buffers in the stock to pick up a new bullet and become ready for the next shot
    3. A bolt, which guides the bullet into the barrel chamber, as the BCG travels forward, and back towards the ejection port, as the BCG travels rearward.
For an NY/NJ legal rifle, we need to avoid the pistol grip that usually protrudes below the lower, and this means the more traditional 'cowboy' rifle stock is in the way of the empty tube the bolt carrier would usually withdraw into. Fightlite manufacture a more traditional looking lower that solves this problem by introducing a 'rat tail' that can angle downwards on the rearward travel and into a thinner buffer in a traditional wooden stock.

But.... The BCG they supply is oriented to align the bolt to the right, for ejection, and for gas ports and travel notches for a right sided upper. Lefties thus receive ejection of hot shell casings & gas on the side of the rifle they have their faces at.

Hence the desire to perform the work aboe.

I understand entirely if you're too busy and this isn't interesting. Either way, happy Christmas and happy new year all ;p


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Re: Custom bolt carrier milling/lathe work ?

Post by Harold_V » Sat Dec 26, 2020 3:41 pm

For clarity, a bullet is the part of a cartridge (the round to be fired) that is the projectile. A cartridge consists of the ignition source (the primer), the powder, the bullet, and the housing, commonly referenced as the brass, or case.

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Re: Custom bolt carrier milling/lathe work ?

Post by pete » Tue Jan 04, 2022 8:44 pm

The individual state laws vary about firearms work, but generally anyone working on firearms other than their own requires a FFL (Federal Firearms License) in most states I can think of. And given the stiff NY gun regulations you can bet on it being mandatory. That FFL also allows you to assume temporary possession of the firearm to remain fully legal while the work is being done. Even as a Canadian I know this. I'm simply adding this as a real caution for anyone even considering doing any work like this. Just having the equipment and knowing how to do the work isn't nearly enough.What the OP needs is a proper FFL & insured shop to do the work and pay whatever it's going to cost to have a licensed pro do so. A simple Google search will pull up numerous company's. Trying to find what appears to be a cut rate price on a hobby machining forum isn't respectful at all and could end up with severe fines and/or jail time. The OP probably means well, but this certainly isn't the place for a request like that. I won't touch any outside work that involves automotive brakes, steering or anything involving vehicle or personal safety, and more specifically any firearms at all. Doubly so for AR's or any semi auto.

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